How would I track a face turning around?
2D Tracking is quite simple and easy to do, just take advantage of the dots and use them as a guideline in your 3d scene to make the rotation of your helmet.  

  

once you set up your tracking scene correctly and you turn your trackers into empties, you can extract transform information from the empties and apply them on your helmet object, by using a Constraint , a hook or even keyframe and rotate the helmet manually if it's a simple mesh.